Plasma impact on 193 nm photoresist linewidth roughness: Role of plasma vacuum ultraviolet light

Abstract

193 nm photoresist patterns printed by optical lithography are known to present significant linewidth roughness (LWR) after the lithographic step that is partially transferred into the underlayers during plasma etching processes. In this study, we identify the factors that impact the photoresist pattern sidewalls roughness during plasma exposure. Among them, plasma vacuum ultraviolet light (110–210 nm) is shown to be the main contributor to the LWR decrease induced by plasma etching processes. In this paper, we also demonstrate the strong correlation between LWR obtained after plasma exposure and the surface roughening mechanisms taking place on top of the resist patterns.